In recent years, the number of devices including touch panel displays such as cellular phones, game machines, and car navigation devices has been increasing. The surfaces of such touch panels are protected by coating layers. Such a layer needs to have anti-scratch properties and anti-fingerprint properties: for example, fingerprints are less likely to be left thereon, fingerprints left thereon are less likely to be noticed, and fingerprints left thereon are easily wiped off. Among these anti-fingerprint properties, the property that fingerprints are less likely to be noticed is considered as being the most important.
A hard coating layer has surface irregularities so that fingerprints left thereon are less likely to be noticed (antiglare hard coating layer). Such an antiglare hard coating layer is produced by, for example, preparing an alumina sol solution by adding water to a mixed solution containing an aluminum alkoxide, an organic solvent, and a chelating agent, applying the alumina sol solution to a plastic film, drying the applied solution to form an amorphous alumina layer, and subsequently immersing the alumina layer into a hot water having an electrical conductivity of 200 μS/cm or less to roughen the surface of the alumina layer.
The formation of the antiglare hard coating layer requires the above-described complex steps. In addition, the antiglare hard coating layer has a drawback that images seen therethrough are not displayed with sufficiently high definition.
There is another hard coating layer that does not have surface irregularities (clear hard coating layer). Since the clear hard coating layer does not have surface irregularities, it provides images with high definition therethrough. In addition, this hard coating layer is advantageous in that it can be readily formed by just applying a hard coating agent to a plastic film and drying the applied agent. However, since the clear hard coating layer does not have surface irregularities, fingerprints left on the hard coating layer are likely to be noticed. Accordingly, there have been demands for a hard coating layer in which fingerprints are less likely to be noticed and fingerprints left thereon are easily wiped off.
To form a hard coating layer in which fingerprints are less likely to be noticed and fingerprints left thereon are easily wiped off, for example, there is a photo-curable resin composition containing a urethane (meth)acrylate that intramolecularly has a polyether skeleton derived from a polyether polyol having a weight-average molecular weight (Mw) of about 1000 to 3000, and has a (meth)acryloyl group at a single end (for example, refer to Patent Literature 1). However, even the photo-curable composition disclosed in Patent Literature 1 does not sufficiently provide ease of wiping off fingerprints. Accordingly, the development of a hard coating agent that can provide high anti-fingerprint properties and high anti-scratch properties has been demanded.